Surge Protection

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    Peter Sandry

    What does anybody think regarding 18th Edition and Surge Protection, and what will your business be doing with general housing stock on rewire/upgrade. I am taking the final statement below on single dwelling units not justifying such protection on a financial assessment of damage to be the ‘get out’ for not installing on social housing single dwellings.

    From BS7671 443.4 Overvoltage control
    Protection against transient overvoltages shall be provided where the consequence caused by overvoltage could:
    (i) result in serious injury to, or loss of, human life, or
    (ii) result in interruption of public services and/or damage to cultural heritage, or
    (iii) result in interruption of commercial or industrial activity, or
    (iv) affect a large number of co-located individuals.

    For all other cases, a risk assessment according to Regulation 443.5 shall be performed in order to determine if protection against transient overvoltage’s is required. If the risk assessment is not performed, the electrical installation shall be provided with protection against transient overvoltage’s, except for single dwelling units where the total value of the installation and equipment therein does not justify such protection.

    Your views and comments gratefully accepted



    Nancy Esslemont

    This is already becoming a common question among AESM members and , as there is scant evidence of many issues with overvoltage surges in the last few years, a number of organisations are reviewing the total value of the installation and equipment to determine if such protection is necessary. The need for SPDs will depend on many differing factors. These include the level of exposure of a building to lightning-induced voltage transients, the sensitivity and value of the equipment, the type of equipment used within the installation, and whether there is equipment within the installation that could generate voltage transients.
    As the demand for higher spec technical equipment – 4k TVs and high spec audio equipment – grows, some organisations are recommending contractors at least ‘offer’ this option.
    In order to make informed decisions it would be good to know to what degreee members have experienced over voltage surges.
    In light of this we will shortly be emailing all members and associates to ask this specific question and will discuss the results at this Spring’s AESM Technical meetings – keep a look out for your email!”


    Extract from a recent internal report:


    The use of SPDs is generally not required in domestic properties and therefore will not be installed as part of a standard installation. The Contract Administrator will highlight any specific properties that are to have it included as part of the installation prior to any works commencing.

    Richard Hart

    I Look forward to the discussion on SPDs in social housing, new builds, rewires and every day maintenance.
    We have just had a training session with Hager, saying that we have to fit them on every job we touch ? I am at the stage of ordering SPD loaded consumer units and standalone devices.
    Now I am unsure if we need to be fitting these.

    Any advice welcome as it will effect our budgets quite a bit !

    Richard hart
    South Kesteven District Coucil

    Gerry Claxton

    We had our annual NICEIC inspection last week and our inspector was under the impression we would not need to fit SPD’s to individual properties, he stated that its our duty to protect the installation not the value of tenants goods,a generic risk assessment would cover this.
    The exception for us would be where we have installed expensive heating systems which I feel warrant protection.

    Gerry Claxton
    Broadland Housing Association

    Vic Oddy

    Reading Richard Harts post, I had to take a breath before posting this response, if Hager are going around telling potential customers that they ‘we have to fit them on every job we touch’. Well that is just misleading and down right wrong, if anything, manufacturers should refer to the Wiring Regulations and give a clear explanation of how to carry out a CRL along with explaining Table 443.2 and the associated Annex A443 the examples of calculated risk level for the use of SPD’s. Then dropping back to Reg 443.4 and going into detail the paragraph following indent iv, referring to single swelling units. Not forgetting all the other associated Regs for SPD’s.
    Hopefully at the next AESM meeting perhaps someone from the IET could have a session on SPD’s I say that as ever since the introduction of the 18th I have heard and seen so much misinformation on the subject and I’m not in anyway saying I understand them in entirety. I can see the introduction of SPD’s by stealth and by the 2nd Amd (or maybe even the 1st which is being worked on) of the 18th everyone will say install or you are not fit for purpose. By the way, even doing the CRL calculation can give you a headache as distances are never truly given by the network operators. (Deep breath now and calm 🙂 By the way don’t even start reading the Notes of Reg 443.1.1 as these will tie you up in knots and lead to an even longer discussion as overvoltages are not just purely of atmospheric origin!

    Richard Hart

    Thank you for your response, I look forward to discussing at the AESM meeting.

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